title: PAX8 is expressed in anaplastic thyroid carcinoma diagnosed by fine-needle aspiration: a study of three cases with histological correlates.
abstract: OBJECTIVE
  It is difficult to diagnose anaplastic thyroid carcinoma (ATC) in a fine-needle aspiration (FNA) sample because, given the loss of morphological and immunophenotypical follicular thyroid features, its cytology resembles that of other undifferentiated neoplasms. Recent studies have shown that immunostaining for paired box gene 8 (PAX8), a transcription factor expressed in normal thyroid, is effective for diagnosing ATCs on histology. The aim of this study was to evaluate whether PAX8 could be used to identify ATCs on cytology also.
  
  
  METHODS
  We selected three PAX8-immunostained undifferentiated FNA samples previously diagnosed as suspected ATCs, whose cell block had been negative for the expression of TGB and thyroid transcription factor-1. Matched histological samples, available in two cases, were also processed for PAX8 immunohistochemistry.
  
  
  RESULTS
  All three FNA samples were PAX8 positive. Two samples that had an epithelioid pattern showed a diffuse, intense nuclear signal. The third sample, which had a spindle-cell pattern, showed less intense and more patchy staining. Matched histology yielded overlapping results.
  
  
  CONCLUSIONS
  PAX8 immunocytochemistry can help cytopathologists to diagnose ATCs.
authors.affiliation: Department of Public Health, University of Naples Federico II, Via Sergio Pansini 5, I-80131 Naples, Italy.
authors.forename: Claudio
authors.initials: C
authors.lastname: Bellevicine
authors.forename: Antonino
authors.initials: A
authors.lastname: Iaccarino
authors.forename: Umberto
authors.initials: U
authors.lastname: Malapelle
authors.forename: Ferdinando Carlo
authors.initials: FC
authors.lastname: Sasso
authors.forename: Bernardette
authors.initials: B
authors.lastname: Biondi
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Troncone
mesh_terms: D000368:Aged; D014408:Biomarkers, Tumor / Q000378:metabolism*; D044963:Biopsy, Fine-Needle; D002277:Carcinoma / Q000175:diagnosis / Q000378:metabolism* / Q000473:pathology; D002467:Cell Nucleus / Q000378:metabolism / Q000473:pathology; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000378:metabolism*; D000072636:PAX8 Transcription Factor; D051761:Paired Box Transcription Factors / Q000378:metabolism*; D065646:Thyroid Carcinoma, Anaplastic; D013961:Thyroid Gland / Q000378:metabolism* / Q000473:pathology; D013964:Thyroid Neoplasms / Q000175:diagnosis / Q000378:metabolism* / Q000473:pathology
chemical_list: D014408:Biomarkers, Tumor; D009363:Neoplasm Proteins; D000072636:PAX8 Transcription Factor; C083325:PAX8 protein, human; D051761:Paired Box Transcription Factors